<p>@giancollii, you’re correct!
Anyways, I think there’s ALWAYS going to be an acid/base/titration question on the FRQ and there will definately be some mc questions on bonding and drawing.</p>
<p>I have drawing down. It’s just the trigonal bipyramid/ octahedral/ square planar craziness that I hate.</p>
<p>Could someone explain this to me?</p>
<p>Q: Excess concentrated aqueous ammonia is added to a solution of nickel (II) nitrate, leading to the formation of a complex ion.
A: Ni^2+ + 6NH3 –> [Ni(NH3)6]^2+</p>
<p>Why are there 6 NH3’s and not 4? I thought it was usually twice the charge on the transition metal.</p>
<p>Guys can someone explain question 1c of the 2002 free response form A, please?</p>
<p>Wouldn’t the relationship be 1:1? Because there is 2 moles H+ to every 2 moles OH-?*</p>
<p>Because Ba(OH)2 will dissociate like this:</p>
<p>Ba(OH)2 ----> Ba2+ + 2OH-</p>
<p>And HOBr will dissociate like this:</p>
<p>HOBr --------> H+ + OBr-</p>
<p>So when you write the equation:</p>
<p>Ba(OH)2 + 2HOBr -----> H20 + Ba(OBr)2</p>
<p>Couldn’t it be simplified to:</p>
<p>2H+ + 2OH- *-----> 2H20?</p>
<p>^ No, because HOBr is a weak acid and can’t be dissociated. Also, we are looking at the molar ratios of HOBr and Ba(OH)2, not hydroxide/hydrogen relationships.</p>
<p>Could someone explain this to me?</p>
<p>Q: Excess concentrated aqueous ammonia is added to a solution of nickel (II) nitrate, leading to the formation of a complex ion.
A: Ni^2+ + 6NH3 –> [Ni(NH3)6]^2+</p>
<p>Why are there 6 NH3’s and not 4? I thought it was usually twice the charge on the transition metal.</p>
<p>Dont worry about that!!! They won’t mark you off for having the wrong amount of ligands.</p>
<p>^ Yea, that’s what I was thinking too. It is OK to have 6 or 4: there are many ways to write ligands.</p>
<p>Titration: You should always know a few points on the graph:</p>
<p>If it’s a weak acid titrated with strong base:</p>
<ol>
<li>Start BELOW 7! (It’s a weak acid to start off with, so it’s acidic!)</li>
<li>The equivalence point is where moles of base added is EQUAL to moles of acid currently present - this point should be ABOVE 7 (It’s a strong base that’ll make it above 7)</li>
<li>You should be able to find the specific volume of the amount of titrant added (the strong base). Simply find the moles of acid that you have to start off with, then figure out how much base you’ll have to add by plugging in the given molarity.
for example … we have 40 mL 0.2M HCl and 30 mL 0.1M NH3.</li>
</ol>
<p>to find the total HCl needed:
- Find moles of NH3 that we have (.003 moles)
- Plugin molarity for HCl to find volume needed: 0.2M = (.003)/Liters
Liters: .015L (that’s the amount needed)</p>
<ol>
<li>The half equivalence point (which is halfway between the beginning and the equivalence point, NOT the equivalence point) (in this case, at .015 / 2 Liters = .0075L is equal to the pKa. You might need this for something like the 2001 question 3, where it gives a table that you can get info from.</li>
</ol>
<p>VICE VERSA FOR STRONG ACID WEAK BASE, and if it’s strong acid strong acid then equivalence is at 7 pH!</p>
<p>could someone tell me an easy way to do this without a calculator? thanks!</p>
<p>What mass of Au is produced when 0.0500 mol of Au2S3 is reduced completely with excess H2?
A. 9.85 g
B. 19.7 g
C. 24.5 g
D. 39.4 g
E. 48.9 g</p>
<p>You have .0500 mol of Au2S3 (note that gold ion has a 2+ charge so this is a really weird molecule, it should be something like AuS), this means there are 2 moles of gold for ever mole of Au2S3. </p>
<p>Thus you have .100 mol of gold, multiply this number by the molar mass of gold - 197 grams, thus you have 19.7 grams of gold.</p>
<p>For the parts when you write the balanced equation:
If you forget to cancel out a spectator ion on both sides of the equation, do you lose both the reactant points AND both the product points? Or would they just deduct it once, and you could still get a max of 2/3 points for the equation?</p>
<p>Also is it out of 5 now? How much is that question worth?</p>
<p>Anddd:
Is a volumetric flask used for acids?
On the 2005 Form B it asked to explain how you would perform a certain reaction. I said I would use a beaker, but it says to use a graduated cylinder to transfer distilled water into the volumetric flask and carry on from there.</p>
<ul>
<li>In a hydrate, there was a question that asked “If heated, the mass is less than before heating. Explain.” I said that it was because, if it was heated, the water from the hydrate would have evaporated.
It explained it as “it would drive the water away”.
Are these two explanations the same? What does ‘driving it away’ even mean?</li>
</ul>
<p>15 total — 5 each x 3</p>
<p>^ so is it 1 reactant, 1 product, 1 for the short answer?</p>
<p>Edit:
If you’re doing a Ksp, Ka, Kwhatever, and you don’t do the ICE table (even if you would have assumed that x was too small, so it would cancel out) would you lose the points?
Would be regarded as you not fully knowing what to do?</p>
<p>How do you determine bond strength? </p>
<p>Also, how would you know if HOBr is a stronger acid than HOI? Isn’t HF a weak acid?</p>
<p>GRAHHH less than 24hrs. I spend the whole afternoon sleeping cause I’ve been doing all nighters. Those critical 12 hrs…</p>
<p>We talked a little about that ^.
I think you would look at the electronegativity of the non-O bond.
HF is a weak acid because F has a very high electronegativity and thus does not easily dissociate, making it a weak acid.
Anyway. Since Br has a higher EA than I, it weakens the H-O bond, because it pulls the O to itself. This makes the H-O bond weaker and thus it is easier to dissociate. I would say that HOBr is a stronger acid than HOI.</p>
<p>Is that right? I hope so. ._.</p>
<p>Anyone have a list of all the strong acids/bases?
I know it was posted somewhere, but I don’t remember where.</p>
<p>Also, for this question:
In which of the following processes are covalend bonds broken?
a. Solid silver melts
b. solid potassium chloride melts
c. solid carbon (graphite) sublimes
d. solid iodine sublimes,
e.glucose dissolves in water</p>
<p>Why is the answer C? They are all physical changes and covalent bond is a chemical bond. Why does the bond break?</p>
<p>^
a) these are metallic bonds.
b) ionic bonds.
c) covalent!
d) not sure what this is. . .
e) since when does glucose dissolve?</p>
<p>I already asked this before, but
What are the differences between an electrochemical and a galvanic cell?
Besides that galvanic cells are spontaneous and electrochemical cells are not.</p>
<p>Strong acids:
HCl
HBr
HI
HClO4
H2SO4 (1st proton only)
HNO3</p>
<p>Strong bases:
Group IA & IIA hydroxides</p>
<p>Graphite is a network solid, which means that the whole thing is one big covalent molecule. In order for it to sublime, some covalent bonds must be broken (this only happens at very high temperatures).</p>
<p>How many significant figures do we use for molar mass on the FRQs?</p>